1. The character introductions were lacking. Having Waller narrate the characters’ backstories to a minor character in a no-stakes infodump was probably not ideal. If Waller’s MO is that she’s ruthless and/or exploitative, would have preferred a scene with her coercing Flag to work on the project and/or why they selected these guys rather than any other high-stakes criminals available. Also, given that virtually all of the characters are total unknowns to most viewers, a smaller team would probably have helped with character development. (Failing that, if you start with a large team of antiheroes, having several deaths would probably have helped raise the stakes and establish a mood).
1.1 Boomerang’s introduction, betraying a partner in a bank heist, was about 1/1000th as effective an introduction as Joker’s TDK bank heist.

2. It probably would have helped if the main mission of the movie had been more shady and/or disagreeable. If a supervillain is ravaging a city, it’s not clear why the government needs a “plausible deniability” option here of unwilling gangsters with guns and bats rather than, say, asking Batman or Wonder Woman to step in. Or that having 6 minor criminal patsies would have helped explain at all why a sorceress wrecked a major city. I feel like a very messy police mission like trying to destroy a major gang and/or killing somebody that’s gone rogue and/or helping a VIP (maybe Waller) deal with a major case of blackmail would have been a better fit.

3. The music selection was ugly. E.g. playing “Sympathy for the Devil” to introduce a shady character with semi-sympathetic goals calls out the viewers as idiots, I think. Not nearly subtle enough. In contrast, Killer Croc got the much more imaginative “Born in the USA”, rather than (God help us) Crocodile Rock.

4. June is the worst archeologist in the world. She spends less than 10 seconds in the temple before twisting the head off a priceless relic that nearly destroys the world. Whoops. Not to be outdone, she falls for the worst soldier in the world, whose superpower is playing golf without a handicap and bungling pretty much everything he touches.

5. The team selection is an odd choice: Harlequin, Killer Croc, Captain Boomerang, Diablo, Katana, Deadshot, and Slipknot. Slipknot and Captain Boomerang are joke characters that contribute very little to the plot. (Seriously, Slipknot’s reason for being on the team is that “he can climb anything”). Harlequin and Deadshot (and secondarily KC and Diablo) feel like a pretty good personality fit for the movie, and the four of them dominate the memorable lines. I would have removed or overhauled CB, Katana, Slipknot, and maybe Rick Flag – they have little impact on the plot, and there just isn’t time.

6. Enchantress feels like a serious mismatch for the protagonists. Someone shootable would probably have created more interesting interactions and better fight scenes, seeing as almost everyone on the team is a badass normal. (The team’s only superhumans are Diablo, Killer Croc, and maybe Katana – not the most intuitive choice for stopping a world-ending threat).

7. Characters raise plausible concerns about Waller’s plans in a fair way (and thoroughly exhaust standard police and military alternatives). In context, it almost feels believable that serious people would agree to this crazier-than-crazy plan. (If we pretend that Batman and Wonder Woman were dealing with some other world-ending threat somewhere else, it almost makes sense). Also, in the interests of making Waller/Flag look better than “totally useless”, it might help if the problem the team had to deal with was not 100% created by Waller being a dumbass.

8. Although this movie did as poorly as Batman vs Superman on Rotten Tomatoes, I think Suicide Squad is considerably better-executed and more entertaining. E.g. Will Smith’s attempted negotiation with Flag and Waller actually did a great job advancing character development, establishing conflicts between characters, and advancing the central plot. I don’t think there were any scenes in BVS that managed any one of those besides maybe Bruce Wayne’s very brief conversation with Diana Prince.

9. Even for a superhero movie, SS asks you to check a lot of realism at the door. E.g. 3 helicopter crashes for major characters without any deaths or injuries. Seriously, it would have been okay to kill off some of these characters. No one in this movie is integral to the success of the DC Universe moving forward. Also, Rick Flag is a notably passive, weak character – besides killing off Slipknot early, he is curiously reluctant to respond to provocations from his team. I was actively rooting for his death.

10. Several of the characters (notably KC, Joker and Diablo) are taken in an unusually gangsta direction. It feels really strange for Joker, who comes across as more sketchy than threatening. For Killer Croc, it got oddly humorous, in a non-PC way.

11. Harlequin’s background as a psychiatrist does not feel like it fits with the rest of the character.
11.1. The sexploitation was actually pretty effective.
11.2. Harlequin getting punched in the face by Batman probably got the loudest laughter from the audience, followed by Deadshot trying to negotiate in prison.

12. Villains threatening worldwide destruction generally don’t give protagonists much to work with. Enchantress felt like a sorry rehash of the most recent Fantastic Four’s Dr. Doom and Green Lantern’s Galactus, even down to the purple vortexes of death and terrible CGI. It’s much harder for characters to interact with a force that has nothing to talk about. Off the top of my head, the only superhero movies with global villains that worked out creatively very well were the Avengers series and Guardians of the Galaxy, and they relied on exceptionally interesting interactions between the protagonists rather than with the villains.

13. Most of the teammates – and Flag and (if you go as far back as Green Lantern) Waller – have a tragic backstory to soften them. I was sort of hoping for at least one character to have an unapologetic Walter White-style “I did it for me. I was good at it.” The closest we got was Harlequin stealing a purse. While that helps reinforce the character’s craziness, maybe something more important to the central plot?

14. Deadshot’s final scene with his kid (helping her with geometry) was surprisingly heartfelt and refreshingly dark. The kid isn’t just a sweet plot device, and it’s probably the closest this movie got to daring. I wish they had tried it more often (e.g. see Deadpool). For example, maybe giving characters more opportunities to do more antiheroic things than stealing a purse? Giving Diablo and Flag more of a pulse? Making Waller competent?

14.1. Deadshot shows off technical expertise in his final scene very naturally – compare how he talks about the geometry of shooting people and the curvature of the Earth to virtually every Fantastic Four conversation about science.

15. It’s so hard to feel for the setting. It’s very generic and, like every DC city besides Gotham, it’s just a soulless cardboard box to wreck. No interesting characters, no interesting places, no distinctive mood to the city… For God’s sake, it’s called Fauxcago “Midway City.” How much personality could it possibly have? PS: Would suggest checking out better noir movies for better alternatives to “dark and rainy all the time.”

16. I didn’t have a watch going during the movie, but it felt like the last 60-75 minutes of the movie were a single, REALLY LONG mission where the characters try breaking into Fauxcago, rescuing a VIP, and ultimately defeating the villain. I strongly preferred the pacing of a movie like Avengers and Incredibles and tens of others, where there are several (much shorter) action sequences that build up to a climactic confrontation with the villain. That would have also made it easier to work in dialogue into scenes than it was for Suicide Squad – e.g. look at how weirdly paced the bar scene is. (The world’s about to end, but hey, let’s talk about Diablo’s backstory!)